I'm currently using (I think) FAHCore 0xa7, at least according to FAHControl's Status, and using FAHControl v7.4.4 on a late 2009 quad-core i7 iMac with 16GB RAM and 1TB HD running under macOS v10.13.6 (17G3025) High Sierra.

Recently (I can't define that, but a couple of months or so I'd guess) I have found everything running very slowly - changing panels, opening applications, navigating through Mail, etc. etc. and I have just paused my latest Unit and things have speeded up dramatically. I am assuming, therefore, that F@H is causing the slowdown.

I have had a look at this august and highly esteemed Forum and there seems to be a bit of trouble with 7.5.1 so I have deferred upgrading as I prefer (if that's the right word) to deal with one problem at a time!

Can anyone tell me why F@H has started to interfere with my normal working? I don't recall experiencing this slowness on "day one" when I started Folding on this iMac back in early 2010.

If you installed the folding client years ago, before upgrading to High Sierra, there is a recommendation to reinstall the client for High Sierra. That removes a workaround that was needed due to a change in the Mac OS a few versions back. That is no longer needed with High Sierra.

7.5.1 brings additional improvements and updates its connections to the folding servers.

One thing I can recommend is changing the core count used by folding to just 4 if you have been using all 8 available threads. In my experience the A7 folding core did not gain much performance using the extra threads provided by hyper threading on the i7 in my 2009 iMac. Reducing to 4 left threads unused by F@h that the OS could use for other applications. High Sierra also has more background services than earlier versions of the OS, folding at 8 threads leaves less CPU for those.

If you do decide to reinstall and/or upgrade to 7.5.1, first finish your current WU. Then run the Uninstaller provided with the F@h software, you might need to run it twice. Use Activity Monitor to check and see if any process starting with FAH is running an run the Uninstaller again if there are any. In the Finder go to the system Library folder, open the Application Support folder and move the FAHClient folder to the Trash. Before emptying the Trash folder, keep a copy of the config.xml file to use for copying and pasting your username, team and passkey information into the reinstalled client. Optionally you can keep log file and folder of logs.

Then reinstall the client. As I mentioned earlier, I would recommend just using 4 threads for folding on your iMac. High Sierra is using more CPU resources, including for rendering the screen as your graphics processor does not support Metal.

Thanks, Joe. The current unit is forecast to finish in 3.84 days so it will be a while before I can try your recommendations - probably next weekend to fit in with work committments. I've clicked the Finish button which, if I recall correctly, stops it getting a new unit when this one finishes.

How do I drop down to 4 threads? Is that done by using the FAHControl "slider"? I have always been running at High so as to give F@H the best run but as mentioned it now seems to be interfering with my own processing and I have now dropped this to Light whilst I'm working and I'll only increase it when the iMac would otherwise be idle.

Incidentally, what brought this to a head was the installation of a new graphics card a fortnight or so ago! System profiler tells me that it is now ...

iBozz wrote:I've clicked the Finish button which, if I recall correctly, stops it getting a new unit when this one finishes.

Right.

How do I drop down to 4 threads? Is that done by using the FAHControl "slider"? I have always been running at High so as to give F@H the best run but as mentioned it now seems to be interfering with my own processing and I have now dropped this to Light whilst I'm working and I'll only increase it when the iMac would otherwise be idle.

You can use the slider, but it's a rather coarse adjustment tool. I'd recommend you start FAHControl, click Configure + Slots + select the CPU slot and click Edit. Near the top, is a setting for The Number of CPU threads this slot should use. (It's probably set to -1) Change it to 4 and Ok/Save the setting.

A 4850 is the standard video card for your model iMac. As long as it was installed correctly with the proper heat transfer pad between it and the heat sink plate inside the iMac, that should not be an issue. The main thing you will be running into with the 4850 iis that it is an older GPU and does not support some of the newer video technologies used by Apple in the recent versions of the OS. So some video display features are not available at all, and others are rendered on the CPU instead of the GPU.

Now to the other questions. Moving the slider to Medium will reduce the core usage to 7, which in practice for most WU's currently available will be reduced to 6. Changing to Light will use half, 4 core. I forget whether that will also change the CPU slot to only working "on Idle" with 7.4.4, but as best as I can recall it does not. If it does, that can be changed.

Otherwise you can change the number using Configure. Click on Configure, it will open a window. Click on Slots, the on the CPU slot shown. Then you can click Edit at the bottom right. The top part of the slot configuration page has the settings for a CPU slot, the default for number of threads(cores) is a -1 which leaves the client settings to the slider. Changing that to 4 and then clicking Ok, and Save will store that setting.

One other note, the longest WU's I get on my iMac which is like yours except only having 12 GB of RAM will complete in about a day. So that 3 day plus estimate might be from the client not having run long enough to settle down to an accurate estimate. That usually takes a 2 or 3 percent of progress since any restart or change in setting that causes the client to restart the WU from the most recent checkpoint.